The invention concerns a method and apparatus for moistening such articles as tools (drills, band saws, circular saws, thread cutters and similar tools as well as stamping, drawing, and sectioning tools) or workpieces (metal or plastic articles being machined, pipes that are being sawn through, or sheet metal being rolled into structural piping for example) with a liquid (such as a lubricant or coolant for tools and workpieces or an adhesive for workpieces), whereby the liquid is removed from a reserve of liquid and supplied by way of a pipeline subject to controlled conditions to a dispenser, a nozzle for example, that is aimed at the area of the article to be moistened, whereby the pipeline has flow controls and a blender for blending a gaseous medium into the liquid.
A method and apparatus of this type is known from the sales literature ACCU-Lube No. 13 b-0387 published by Rexim Werkzeugvertriebs-GmbH, 7133 Maulbron 2, Federal Republic of Germany.
A mixture of oil and water ("drilling water") is usually employed to lubricate and cool tools that machine workpieces. Large volumes (e.g. several hundred liters an hour) of the mixture are supplied to the area being machined and must be retrieved below the machine, a procedure that is inconvenient and detrimental to the environment and involves considerable expense for processing the used mixture.
Such shaping procedures as stamping, drawing, and rolling also require moistening of the tools (e.g. rollers, dies, or drawing tools) and workpieces (e.g. piping) with a lubricant.
The method known from the aforesaid literature employs a lubricant that, although it is liquid, is supplied only in very small quantities to the tool's cutting surface by way of flow controls. This approach eliminates the need to recover large volumes of lubricant, which is never 100% effective, and accordingly reduces damage to the environment and maintains a substantially cleaner shop.
The same literature describes a device for carrying out the method, wherein liquid, which consists of a fatty alcohol, is supplied from a reservoir through flow controls and subject to electromagnetic valves to tubing. The tubing's nozzle can be secured with a magnet to the housing of the tool in the vicinity of the processing area. As the procedure is initiated, the lubricant is supplied to the area being lubricated, that is, either by a manually activated two-way switch, by a pedal, or by way of an electromagnetic valve.
As is evident from an illustration in the publication, the flow controls operate by compressed air and forward a prescribed volume of lubricant to the site being lubricated when activated by the switch, pedal, or valve.
Tests of a device constructed in accordance with this illustration have demonstrated certain drawbacks. It is impossible to optimally control the flow of liquid during heavy-duty operations. When a bundle of pipes is sawn with a circular or band saw for instance, the known device demands relatively a lot of lubricant to prevent the blade from getting jammed in the pipes and breaking. This means of course that the used lubricant must be recovered and removed.
The probable causes of this unsatisfactory behavior on the part of the known device are that the precision of its flow controls leaves a lot to be desired and that the lubricant cannot be distributed uniformly enough over the operating field of the tool or workpiece, so that excess lubricant must be applied to ensure that enough reaches the least accessible areas.
To prevent malfunctions in fact, the operator must always provisionally adjust the supply of lubricant high enough to ensure a constant excess, not only contaminating the shop but leaving large volumes of lubricant on the workpiece that must be removed later, to say nothing of the unnecessarily high consumption of lubricant entailed by this method.